The Specific Induction of Osteosarcomas in Different Mouse Strains after Injections of super(239)Pu Citrate

Lifetime bone tumor induction by the injection of a bone-seeking alpha emitter, super(239)Pu citrate, was compared among 630 female mice from three strains (C3H/He, C57BL/6 and B6C3F sub(1)) showing different genetic backgrounds for carcinogenesis. Bone tumors, mostly osteosarcomas, appeared early during the period from 200 to 600 days after the injection, showing an almost similar dose responsiveness with a peak incidence of 50% to 63% at skeletal doses of 2-3 Gy, in all mouse strains. The primary sites of bone tumors from these strains were also predominantly distributed in 80% to 90% of the skeletal bones, which had well-developed trabecular bone surfaces and large vascular sinusoids. The frequency of lymphoid neoplasms was significantly lower than the control values, and some appeared earlier at the higher injected doses than those of the controls. Fewer or no myeloid leukemias were found in all the control and injected animals, and the incidences of other solid tumors decreased, reaching zero at doses where the maximum incidences of bone tumors were noted. These findings indicate that osteosarcoma is the only specific tumor commonly observed among different mouse strains following the injection of soluble plutonium compounds.